Editing Earth's magnetic field (section)

=== Dipolar approximation ===
[[File:Geographical and Magnetic Poles.png|thumb|Relationship between Earth's poles. A1 and A2 are the geographic poles; B1 and B2 are the geomagnetic poles; C1 (south) and C2 (north) are the magnetic poles.]]
{{See also|Dipole model of the Earth's magnetic field}}
Near the surface of the Earth, its magnetic field can be closely approximated by the field of a magnetic dipole positioned at the center of the Earth and tilted at an angle of about 11° with respect to the rotational axis of the Earth.<ref name="NGDC">{{cite web |title=Geomagnetism Frequently Asked Questions |url=https://www.ncei.noaa.gov/products/geomagnetism-frequently-asked-questions |access-date=21 October 2013 |publisher=National Geophysical Data Center}}</ref> The dipole is roughly equivalent to a powerful bar [[magnet]], with its south pole pointing towards the geomagnetic North Pole.<ref>{{cite news |first=Anne |last=Casselman |title=The Earth Has More Than One North Pole |newspaper=Scientific American |date=28 February 2008 |url=http://www.scientificamerican.com/article.cfm?id=the-earth-has-more-than-one-north-pole |access-date=21 May 2013}}</ref> This may seem surprising, but the north pole of a magnet is so defined because, if allowed to rotate freely, it points roughly northward (in the geographic sense). Since the north pole of a magnet attracts the south poles of other magnets and repels the north poles, it must be attracted to the south pole of Earth's magnet. The dipolar field accounts for 80–90% of the field in most locations.<ref name="MMMch2" />
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